The present invention relates to apparatus for amplifying electrical signals, and more particularly to apparatus for interconnecting plural amplifiers so as to achieve high gain amplification of an RF signal.
One known form of multistage RF amplifier employs plural class C, common emitter (CE) transistor amplifier stages connected in parallel to amplify a common input signal, with the outputs of the plural amplifier stages being additively combined to produce a single amplified RF signal having a power level greater than any of the individual RF amplifier stages could deliver by itself. One disadvantage of this approach is that the input signal which is applied to the plural stage amplifier must have an adequate power level to drive all of the stages at the same time, since they operate in parallel.
It would be desirable to provide a multistage amplifier having reduced driving requirements, or to provide an amplifier wherein fewer stages could be used to produce a given level of power amplification. It would further be desirable to employ the amplifier stages used in the previous amplifier designs, rather than to design an entirely new amplifier module for use in such multistage amplifier embodiments.